Direct Shear Test

Q. In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are $0.6kg/c{m}^2$ and $1kg/c{m}^2$ respectively. The angle of internal friction of the sand will be nearly.

1. ${25}^o$
2. ${31}^o$
3. ${37}^o$
4. ${43}^o$

Q. The shear strength of a cohesionless soil is

1. Proportional to the angle of shearing resistance
2. Inversely proportional to the angle of shearing resistance
3. Proportional to the tangent of the angle of shearing resistance
4. None of the above

Q. In a shear test on cohesionless soils, if the initial void ratio is less than critical void ratio, the sample will

1. increase in volume
2. initially increase in volume and then remain constant
3. decrease in volume
4. initially decrease and then increase in volume

Q. Consider the following features of direct shear test:
1. Failure takes place on the predetermined plane.
2. It is a quick test.
3. Drainage conditions cannot be changed.
4. Failure of the sample is progressive.
Which of these are the disadvantages of direct shear test?

1. $1,2$ and $3$
2. $1,3$ and $4$
3. $1,2$ and $4$
4. $3$ and $4$

Q. A direct shear test was conducted on a cohesionless soil (C=0) specimen under a normal stress of 200$KN/m^2$. The specimen failed at a shear stress of 100 $KN/m^2$. The angle of internal friction of the soil (degree) is

1. 26.6
2. 29.5
3. 30.0
4. 32.6

Q. Which of the following statement(s) is / are incorrect regarding 'Direct shear test'?
1. The sample fails along the weakest plane
2. Test is conducted in a controlled drainage conditions
3. The test is quick, inexpensive and suitable for sands

1. 1 and 3
2. 3 only
3. 2 only
4. 1 and 2

Q. Which one of the following is the reason for the likelihood of erroneous results of a Direct Shear Test on a saturated clay sample?

1. The test amounts to undrained test
2. Failure plane is predetermined
3. Progressive failure might take place
4. Drainage conditions are not controllable

Q. A $3m\times 3m$ square precast reinforced concrete segments to be installed by pushing them through an existing railway embankment for making an underpass as shown in the figure. A reaction arrangement using precast PCC blocks placed on the ground is to be made for the jacks.
At each stage, the jacks are required to apply a force of 1875 kN to push the segment. The jacks will react against the rigid steel plate placed against the reaction arrangement. The footprint area of reaction arrangement on natural ground is 37.5$m^2$. The unit weight of PCC block is 24 $kN/m^3$. The properties of the natural ground are: c = 17 kPa; $\varphi ={25}^{\circ }$ and $\gamma =18kN/m^3$ . Assuming that the reaction arrangement has rough interface and has the same properties that of soil, the factor of safety (round off to 1 decimal place) against shear failure is

1. 2.0187

Q. Following observations are made during direct shear test on sand:
Normal load at failure = 250 N
Shear load at failure = 175 N
Cross-sectional area of sample = $36c{m}^2$
The angle of internal friction (in radian) is

1. 0.61
2. 0.71
3. 0.81
4. 0.91